I downloaded the Gmail app for my iPhone 5C a week ago, not expecting much. I was proven wrong. The user experience blew my mind.
Here's how my typical use case goes:
Upon reading the email on mobile, I might not take immediate action, because I might need to work on my laptop first, before shooting of a response email. This is where Gmail came in handy for me: I can easily mark the email as "unread", and check back later on my laptop.
Even if I do need to quickly fire back a response, the interface is fluid enough, and gets the job done.
I'm officially choosing Gmail's native app, over Apple's Mail client, because it fits my use case. Gmail is feature rich, highly responsive and not intrusive at the same time. The new "promotions" and "social" tab is a neat feature, that allows me to receive only important emails. For eg: I won't receive notifications when I get a new follower on Twitter, or some promotional email from MailChimp.
The Gmail app will only continue to be better over time, due to the machine learning techniques employed on the Google's backend.